Also another option is to use 01-05(iirc) WRX front springs and 05-09 LGT springs.
The BE/BH Leggys got a multilink rear that the Impreza did not get, that carried on into the 4th Gen Leggys. Tein also shows the 08+ WRX uses the same front spring P/N as the 00-04 Leggy on their site.